1. Field of the Invention
The present invention relates to an image display device that displays images on a screen with a laser beam as a light source.
2. Description of Related Art
In an image display device that displays images on a screen with a laser beam as a light source, since a laser light source is a light source of very high energy, the laser beam when touched therewith may cause some danger to the human body. When a laser beam from a light source undergoes normal beam modulation by the use of constituent elements of an optical system, the energy of the laser beam that is irradiated on a unit area induces no problem because of reduction of the intensity thereof to the degree that does not cause harmful affect to the human body.
However, there is a case that due to a trouble of, for instance, a lens for beam modulation, such a problem occurs that the laser beam is not sufficiently modulated as a beam. Also when being in a state where the beam modulation is not implemented, that is, when the laser beam is irradiated concentrated in a small area, the laser beam is kept in a state where the laser beam is irradiated without beam modulation, and information that the instrument is in such a state is not given outside. When the laser beam touches the human body, there is the likelihood of causing serious problems such as a burn, lowering of eyesight, loss of eyesight or the like. In addition, according to PL Law (Product Liability Law), liability of the manufacturers is called on. Accordingly, serious economic damage might be given on the manufacturers.
As mentioned above, in the case of an image display device in which an existing laser beam is used as a light source being employed, when due to trouble of a lens for beam modulation or the like, the beam modulation of laser beam is not implemented sufficiently, serious problems might result.
An object of the present invention is to prevent accidents due to laser beam of an image display device from occurring, wherein images are displayed on a screen by the use of laser beam of high energy as a light source.